Prevent NPEs in NLSes

NLSs (rightly) assume that the SBN they get from
onNotification[X] calls will not be null. If it is, log and bail early.

Bug: 78279961
Test: reboot device
Change-Id: Id2bba6b15aeea2d701d92d6c63022463f0f8c1df
2 files changed